Field Test and Finite-Element Model of a Skewed Railroad Truss Bridge

Abstract

The skew angle affects the geometry and design of a bridge in many ways. For example, skew angles greater than 20° will affect the bending moment and the shear force in an exterior beam. The U.S. Army Engineer Research and Development Center performed a full-scale load test on a skewed railroad steel truss bridge at Fort Leonard Wood, Missouri, in July, 2007. The superstructure of the bridge was instrumented with 42 reusable strain transducers to accurately measure the structure’s response to a 260 kip train engine. Analyses were carried out to determine the effect of the skew angle in that response. A three-dimensional finite-element model (FEM) was developed from the data collected during the load test. The measured internal axial forces compared satisfactorily with the results from the FEM analysis. After the calibration of the model, the results indicated that the skew angle decreased the internal axial forces by approximately 16%, which was comparable to current design practice.